The present invention relates to a sensing system, and, more particularly, to a sensing system including a sensor assembly for sensing an obstruction between a movable panel or closure member and a frame so as to prevent further movement of the panel upon the obstruction.
Many devices have motor driven panels which open and close upon actuation of a switch. For example, vehicles are provided with venting sunroofs. The sunroofs have a movable roof panel which is slidable between opened and closed positions in an opening formed in the roof of the vehicle as well as being pivotable about one end thereof to raise a rear edge of the roof panel a small amount above the stationary roof structure into a venting position. Conventionally, the movement of the panel is controlled by manually operating a switch disposed within the interior of the vehicle. To initiate movement of the panel from either in its fully opened or vented position, the operator engages the switch until the panel is in a closed position. Certain sunroofs include an express close operation wherein actuation of a switch and thereafter release of the switch will close the panel without the need to continuously digitally actuate the switch.
In certain circumstances, while closing a movable panel from a partially or fully opened position, a person or object in the way of the closing panel could become injured or damaged.
Sensing systems have been developed to sense when an obstruction is between a movable panel and a stationary frame during closing of the panel. One such system is disclosed in U.S. Pat. No. 4,621,223 to Murakami et al. which uses a sensor mounted along an edge of an opening for a door, window or roof panel. The sensor comprises a pair of conductive, metal strips mounted on an insulating sheet. A second insulating sheet is interposed between the metal strips and includes a plurality of openings therein. A resistor is connected between the metal strips to produce a nominal resistance. When a unidirectional force is applied to the sensor due to contact with an obstruction, the resistance value of the sensor is changed from its nominal value. This resistance change is detected which signals a controller to reverse rotation of a motor which drives the door, window or panel preventing damage to the obstruction. This conventional sensor is expensive to manufacture since two elongated, conductive metal strips must be provided. Further, these rigid metal strips tend to reduce the overall flexibility of the sensor and thus, may reduce the sensitivity thereof and may prohibit use of the sensor in other obstruction sensing applications. In addition, this sensor may not always actuate when contacting an obstruction, since the packaging containing the sensor may not adequately transmit a non-unidirectional input force to the sensor.
Accordingly, a need exists to provide an improved, cost effective sensing system which senses when an obstruction is between a movable panel and a stationary frame during closing of the panel.